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<p><a name=5.2.3></a><b>5.2.3 Splits</b></p>

<p>Split codes: Sfs; fsp; rsp.</p>

<p>These always link together such that an 'Sfs' service always follows from an
earlier 'fsp' (split from front) or 'rsp' (split from rear) service.</p>

<table class=MsoTableGrid border=1 cellspacing=0 cellpadding=0
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  padding:0cm 5.4pt 0cm 5.4pt'>
  <p><span style='font-size:11.0pt'>Start new service from a split</span></p>
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  border-left:none;padding:0cm 5.4pt 0cm 5.4pt'>
  <p><span style='font-size:11.0pt;color:blue'>HH:MM;Sfs;service ref. of the
  train that splits </span></p>
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  <p><span style='font-size:11.0pt'>Front split</span></p>
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  <td width=308 valign=top style='width:231.05pt;border-top:none;border-left:
  none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  padding:0cm 5.4pt 0cm 5.4pt'>
  <p><span style='font-size:11.0pt;color:blue'>HH:MM;fsp;new (split-off)
  service ref.</span></p>
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  <p><span style='font-size:11.0pt'>Rear split</span></p>
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  <p><span style='font-size:11.0pt;color:blue'>HH:MM;rsp;new (split-off)
  service ref.</span></p>
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<p>A train may split from the front, where the new split-off service appears in
front of the original service, or from the rear. The line that contains these codes also
contains the service reference for the split-off service. The split-off service
has code 'Sfs' (start from split) and also the service reference for the
service that it splits from. </p>

<p>One thing to beware of during operation is that the platform (or non-station location) at which the
split occurs must be long enough to allow it. The condition is that both trains
must be at a platform after the split, although only one element of the train
(half its length) need be at a platform. Additionally two of the final
four elements that the two trains stand on must overlap the two elements of the original
train. Within those conditions RailOS will try to ensure that the front of the front train doesn't exceed the end of the platform so as to remain protected by a signal that lies one element beyond the platform. These conditions mean that the original train may be (and usually is) repositioned during the split. Therefore the minimum platform length is two elements, providing there is a track element linked at each end. If one end is a buffer then the platform
must be at least three elements long. When the timetable is first validated
(either during editing or on loading for operation) a check is made that each
location at which a split occurs has at least one platform that is long enough,
but it is up to the signaller to ensure that the actual platform that the train
arrives at is long enough for the split. If it isn't then a warning message is
given and the train will need to be moved under signaller control to find an
appropriate platform. To be safe it is best to ensure that platforms where splits are to occur are several elements long. A second thing to beware of is to try to ensure that
after a split both trains lie behind a protecting signal. If one of the trains
straddles a signal, then that signal does not provide any protection, and when
the train's departure time is reached it will depart possibly without a route having
been set. Note that because the number of train elements that will be standing
at platforms is maximised, it may be necessary to move an obstructing train
further away than would appear to be strictly necessary, but when it has been
moved sufficiently the split will occur.</p>

<p>When trains split the proportion of mass and power that are transferred to the split-off train can vary between 1% and 99% for the mass, and between 0% and 100% for the power.  0% for power is useful when dropping off wagons or coaching stock.  To apply this feature a fourth element is added to the end of the split command e.g. 09:48;fsp;0D00;25-35.  In this example the split-off train has 25% of the original mass leaving the train that splits with 75%, and has 35% of the power leaving the train that splits with 65%.  In all cases the brake force remains in the same proportion as the mass so braking performance stays the same as for the original train.  The maximum speed also remains the same as for the original train.  If no fourth element is provided the mass and power split evenly between the two. 
</p>

<p>If a train that splits at a location has a minimum dwell time (MDT) specified for its arrival (see arrival information in section 5.2.1) then the front train remains at the location for at least the MDT whereas the rear train remains at the location for at least the MDT + 30 seconds.  This allows the front train to depart first.</p>


<p>See <a href="5.111w8h.htm">section 5.11</a> for some important aspects that
will help to avoid errors.</p>

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